BR_PORT_BITS
p->priority = 0x8000 >> BR_PORT_BITS;
#define BR_MAX_PORTS (1<<BR_PORT_BITS)
return ((u16)priority << BR_PORT_BITS)
| (port_no & ((1<<BR_PORT_BITS)-1));
#define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)